1. Field of the Invention
The present invention relates to a manufacturing method of a silicon-on-insulator (SOI) substrate and a manufacturing method of a semiconductor device using the SOI substrate. In particular, the present invention relates to a technique by which a large area single crystalline semiconductor film is formed over a substrate having an insulating surface such as glass by an SOI bonding technique.
2. Description of the Related Art
In recent years, a technique for forming a semiconductor device such as a thin film transistor (TFT) using a semiconductor thin film (the thickness of several nanometers to several hundreds nanometers) formed over a substrate having an insulating surface such as glass has been attracted. Thin film transistors are widely applied to electronic devices such as an IC and an electro-optical device. In particular, urgent development is required on thin film transistors as switching elements of image display devices.
In addition, instead of silicon wafers formed by thinly slicing a single crystalline semiconductor ingot, which are widely used in manufacture of semiconductor devices, semiconductor substrates called silicon-on-insulator (SOI) substrates that each has a thin single crystalline semiconductor layer over an insulating surface have been developed. An integrated circuit using an SOI substrate has been attracting attentions, because parasitic capacitance between a drain of a transistor and the substrate can be reduced and performance of a semiconductor integrated circuit can be enhanced.
As a method for manufacturing such SOI substrates, an ion implantation separation method is known. For example, ions of hydrogen or the like are implanted to a silicon wafer provided with a silicon oxide film on its surface to form a microbubble layer serving as a cleavage plane at a predetermined depth from the surface, and the silicon wafer is bonded to another silicon wafer. Then, heat treatment is performed to separate a thin single crystalline semiconductor film (SOI film) at the cleavage plane, and an SOI layer substrate is formed.
Further, a method for forming an SOI film over a substrate having an insulating surface, e.g., a glass substrate, has been attempted. One example of semiconductor devices using SOI substrates is disclosed by the present assignee (see Reference 1: Japanese Published Patent Application No. 2000-12864).